Given the task definition and input, reply with output. In this task, you are given news articles and you need to generate a highlight, i.e., a short summary, with a maximum length of 10 lines.

(CNN) -- Chelsea have completed the signing of England international defender Gary Cahill from Premier League rivals Bolton Wanderers for a fee of $10.7m. The 26-year-old finalized his protracted move on Monday after agreeing personal terms and passing a medical, making it the biggest English transfer so far during the January window. Cahill has signed a five-and-a-half year contract with the London club, despite doubts beginning to surface about the deal due to the length of time negotiations over his financial terms took. Who are football's top January transfer targets? He told the official Chelsea website: "Chelsea are a massive club. They look to win trophies season in season out and it is a big opportunity for me to be a part of that. "Opportunities like this, you just can't turn down," added Cahill, who has won seven England caps and will be battling with Brazilian David Luiz to partner England captain John Terry at the heart of the Chelsea defense. Speaking on Saturday about Cahill's impending arrival, Chelsea manager Andre Villas Boas told reporters: "He has good technical abilities which is important in the way we want to play and to implement our philosophy. "Competition will be tight for him but we brought him in to become better as a team." Cahill joined Bolton from Aston Villa in January 2008 and developed into one of England's top defenders during his four years at the Reebok Stadium. However, he had already indicated he was not prepared to sign a new contract, meaning Wanderers were forced to sell him or lose him for free at the end of the season. Meanwhile, the Carlos Tevez transfer saga has taken a new twist after Inter Milan president Massimo Moratti confirmed the Italian club had made a $31.7 million bid for Manchester City's Argentine striker. Speaking to reporters after Inter's 1-0 victory over city rivals AC Milan, Moratti said: "Our offer is 25 million euros -- now it depends on them whether they accept it or not." Inter have emerged as favorites to sign Tevez, after Milan pulled out of the race last week when their plan to sell Alexandre Pato to Paris St Germain fell through following the Brazilian's decision to stay at the San Siro. Ironically big-spending PSG now seem the only realistic challengers for Tevez, who has fallen out of favor at City after refusing to come off the substitutes' bench during the 3-1 Champions League defeat at Bayern Munich earlier in the season. Elsewhere in the Premier League, Blackburn central defender Chris Samba has handed in a written transfer request, despite Rovers manager Steve Kean saying the player was not for sale. The Congolese international has already been the subject of a rejected bid from QPR, while title-chasing Tottenham and French big spenders PSG have also been linked with the player. Samba issued a statement saying: "In my five years at Blackburn I have always given 100% in every game I have played. I have had several opportunities to leave but I have always stayed. "I have decided now is the right time for me to pursue a new challenge and I have asked the club to respect my decision and allow me to leave." In other transfer news, Barcelona have announced that French defender Eric Abidal has signed a new deal with the club. The 32-year-old, who had been linked with a move away from the Nou Camp, is now contracted to the European champions until June 2013, with an option to extend the deal until 2015. Abidal has made 177 appearances in four years with Barca, winning the Champions League twice and the Spanish La Liga three times.

Chelsea have completed the signing of Bolton central defender Gary Cahill .
The 26-year-old England international joins Chelsea for a fee of $10.7 million .
Cahill's transfer is the biggest in England so far during the transfer window .
Eric Abidal signs a new contract with Barcelona to end speculation about his future .